Plus it made a nice double in-joke: Not only does poor Chekov (and the audience!) have to worry about him meeting the fate of a typical redshirt, but in the Prime Universe (at least according to the novels) Chekov was a redshirt working down in Engineering when the original Khan came aboard the Enterprise, and he apparently put up enough of a fight when the Augments took over to earn Khan's notice. "I never forget a face..."